To assess the impact of Deep Brain Stimulation (DBS) parameters on stimulation-induced dyskinesias (SID) in Parkison’s Disease (PD) patients.

SID resemble levodopa-induced dyskinesias and can be challenging to manage. Adjusting stimulation parameters (contact(s), configuration, amplitude, frequency and pulse width) has shown some benefit, but currently, no standard approach exists to reduce SID without sacrificing the efficacy of DBS for PD motor symptoms. This study investigates optimization of amplitude and frequency for improved SID. 

PD patients implanted with DBS (N=10) completed baseline Unified Parkinson’s Disease Rating Scales (UPDRS) and Unified Dyskinesia Rating Scales (UDysRS) in the ON-medication state. DBS programming parameters were systematically adjusted to eight settings using two amplitude levels and four frequency levels (155, 125, 85, and 55 Hz). With each adjustment, patients rested for one minute then open/closed their fist for one minute. Motor symptoms in each trial were scored using modified UPDRS and UDysRS.

Patients included 7/10 male, 8/10 right-handed, with average age70.1, and average symptom duration of 8.3 years. DBS targets included 3/10 globus pallidus internus (GPi) and 7/10 subthalamic nucleus (STN). Average baseline UPDRS was 17.3, UDysRS(dyskinesia) was 17.9, and UDYsRS(dystonia) was 2.3. Mixed linear model statistical analysis found that higher frequency and higher amplitude trended toward higher dyskinesia (p=0.481, p=0.826), and the interaction between lower frequency and amplitude trended toward lower dyskinesia (p=0.153). The interaction between amplitude and frequency trended toward decreased tone (p=0.067), decreased bradykinesia (p=0.071), and significantly decreased tremor (p=0.002). Higher amplitude and lower frequency resulted in improved tremor, tone, and dyskinesia.

Higher frequencies, regardless of amplitude, were associated with lower tremor, tone, and bradykinesia, but higher dyskinesia. However, lower frequencies with higher amplitudes improved tremor, tone, and  dyskinesia. These results suggest this stimulation paradigm may be beneficial for patients with SID. Further exploration, including physiologic correlation with clinical symptoms, is underway.